when you configure a banner you start with a delimiter character (for example banner login %)
everything you type (letters of text, spaces, Carriage return/new line, etc) becomes part of the banner until you type the delimiter character (% in the example I used). So get the router to end one line and begin a new line by using the Enter key.
The difference is where in the connection sequence the banner messages are displayed. The MOTD banner is displayed at the beginning of the connection (before any prompt is displayed) while the login banner is displayed after the prompt when you are logging in.